Lamp filament support



March 9, 1965 T. BERLINGHOF ETAL 3,173,051

LAMP FILAMENT SUPPORT Filed April 2, 1963 lrwewftos: The@ Bevbivwghorflolff- Kiesel,

United States Patent O M' 3,173,051 LAMP FILAMENT SUPPRT Theo ABerlinghof, Heldenhem-Mergelstetten, and Rolli Kiesel, Aalen, Germany, assignors to Patent-Treuhand- 'Gesellschaft fr elektrische Glhlampen nLhl-l.

Filed Apr. 2, 1963, Ser. I\lo.2t'i9,972 Claims priority, applicatif; Germany, Apr. 19, 1962,

s claims. (Ci. sis-27a) This invention relates generally to electric incandescent lamps, and -more particularly to lamps having tubular bulbs or envelopes containing an axially extending helically coiled filament.

In order to maintain the lilament in the envelope axis `it has been the practice to use supports of wire or sheet clined positions when the lamp is moved, whereby the lilament coil becomes distorted.

lt has been attempted to overcome such tendency to tiltby making thesupport turns of greater diameter than the inner diameter of the envelope, the said turns being compressed during insertion into the 'envelope so that they abut against the envelope wall. However, insertion of such supports into the envelopes of relatively long tubular .lamps becomes difficult when there are many separate supports and they are clamped tightly to lthe filament coil and must therefore be inserted into the envelope together with the filament coil. ln order to overcome these difficulties of insertion, during which the lament coil may easily be distorted and damaged, it has been proposed to insert the wire supports separately into the envelope and to make that part of the support which holds the filament coil so large that the coil may be inserted subsequently through such holding sections of the support. With this type of support it is not possible to clamp the support tightly to the filament coil.

It is an object of the present invention to provide a novel support structure which will obviate the above mentioned disadvantages.

In accordance with one aspect of the invention, the improved support is made of a single length of wire formed to provide two spaced circular turns or rings which extend over at least halt the envelope circumuference and abut against the envelope wall, and two straight wire sections which extend toward each other from respective said turns and substantially parallel to the envelope axis, and an intermediate portion between said straight sections and which is clamped to the filament coil. Since the circular turns are maintained in fixed spaced relationship by the straight wire sections, tilting of the support is prevented.

In accordance with a further aspect o the invention, that part of the wire support which is clamped to the filament coil consists of a curved section or loop and two clamping legs on respective sides of the loop, said legs extending from the lilament coil to the tube wall. The straight wire sections continuing from the clamping legs are then suitably located along the same longitudinal surface line of the envelope. In case the filament is a simple single helical coil the clamping part of the wire support may encompass Ia coil turn or the wire itself. In the case of a coiled coil filament a turn of the primary coil is preferably held by the clamping part of the support. In lorder to assure reliable clamping, the clamping legs 3,173,051 Patented Mar. 9, 1965 ICC of the wire support are preferably curved in an opposite `sense to the curvature of the adjoining portions Vo Vthe loop and in overlapping scissor-like relationship, i.e., 4in the form of a figure `8.

Incandescent Vlamps in which an addition of `iodine `to the gas -fiilling prevents blackening ofthe lampenvelope by vaporized Afilament .particles and which have a very small enevlope in proportion to the highly loaded short coiled coil filament, consist ot a quartz tube which is sealed at both ends by means `of pinch `sealsthaving foil portions of lead-in conductors embedded therein and which is evacuated and filled with gas through anexhaust tube attached to the 4envelope wall. The exhaust tip re maining after sealing oit the'exhaust tube maybe tutilized to prevent sliding of `the wire support along 'the envelope. To that end, an offset crimp or Yfold may be formed in the wire support to engage in the cavity formed Vby the exhaustrtip and thereby prevent displacement of the support along the envelope axis, particularly with the lamp positioned vertically. The said crimp or `fold may, of course, also engage any other depression -or cavity -pro vided in :the `envelope wall for that purpose.

For a further understanding of the invention reference is directed to `the following detailed description and to the accompanying drawing wherein:

FIG. l is aperspective View of aporton of atilamjent coil and a wire support member in accordance with the invention;

FlG. 2 is a side view, `partly in section, `of a tubular filament lamp containing the support member shown in Fifi. lgand FIG. 3 is a cross section of a lamp having a modified form of support. p

Referring to FlG. 1 of the drawing, `tl'iere is shown a coiled coil `filament 1havinga 'straight axis A. The wire support comprises two turns or circular loops 2 and 3 lying in spaced planes which are parallel to each other and perpendicular to the axis A, two straight wire sections d and 5 in substantial alignment parallel to the axis A, and an intermediate retroverted link-like clamping portion. The said clamping portion comprises a loop 6 at the end ot two curved clamping legs 7 and S which are arranged in scissorslke overlapping relation forming a figure 8 so that one turn of the primary coil oi the filament 1 is iirmly enclosed thereby. When the filament 1 and the wire support are inserted into the lamp envelope the coil axis A lies substantially in the axis of the envelope.

in the lamp shown in FIG. 2 the coiled coil filament 1 of tungsten wire has its single coiled ends attached to respective inner lead wires 1l) of tungsten. Each lead wire itl is welded to a molybdenum foil 11 with a thin platinum plate (not shown) interposed therebetween. Each foil ll is connected to an outer molydenum lead wire l2. The foils 11 are hermetically sealed in pinch seals 14 at respective ends of the tubular quartz envelope 1.3. Each of the pinch seals llt preferably has a cross section in the shape of an I or a double T. The lamp envelope l?, is exhausted and filled with gas through an exhaust tube which is subsequently tipped olii to leave the exhaust tip l5. The gas filling may consist of nitrogen at a pressure of 600 mm. Hg and iodine vapor at a partial pressure of l5 mm. Hg. The wire support is like that shown in FlG. l. The dia-meter of the support turns or rings 2 and 3, when relaxed, is somewhat greater than the inner diameter of the Venvelope 13. The wire support, with the coiled coil ilarnent 1 clamped thereby and with the support turns 2 and 3 compressed, may be threaded relatively easily into the rather short envelope i3 without damaging the filament.

By way of specific example, a lamp of the type shown in FIG. 2 may be rated to consume 750 watts on a 220 j K4.; volt supply. The outer diameter of the envelope 13 is vabout 1'4 mm. and the total length of the envelope is 68-69 mm. For lamps having a longer envelope and a porportionately longer filament, several Wire supports may be used.

The lamp shown in FIG. 3 is similar to that shown in FIG. 2, including the tubular envelope 13', exhaust tip 15' and coiled coil filament 1. However, in this case the turn or ring 2' of the wire support is formed with an olfset crimp or fold 16 is engaged in the cavity formed by the exhaust tip 15. It will be evident that in this case the exhaust tip 15 may be offset from the center of the envelope 13 so as to be in alignment with the turn 2 of the wire support member.

By virtue of the crimp 16 engaging the exhaust tip 15', the wire support and the filament coil 1 are retained in position even when the lamp is subjected to shocks while in a vertical position. With this construction it is not necessary that the support member turns be proportioned to abut against the envelope wall under compression; they are preferably formed to a diameter which is somewhat smaller than the inner diameter or" the envelope. When the support member, together with the filament, is threaded into the envelope 13', it is only necessary to compress the turn 2 containing7 the crimp 16 until the said crimp 16 snaps into the exhaust tip 15.

it will be evident that the crimp or fold 16 may be provided in one of the straight Wire sections 4 or 5 the support member and it may be engaged in any suitable indentation of the envelope other than the exhaust tip 15.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric incandescent lamp comprising a tubular envelope having therein a helically coiled filament extending axially of the envelope and supported from the inner envelope wall by a wire support member, said support member comprising a single length of wire formed to provide a pair of circular turns extending over at least half the circumference of the inner envelope wall and spaced apart longitudinally of the envelope, straight wire sections extending toward each other from respective said turns longitudinally of the envelope, and an intermediate retroverted link-like part between said straight sections extending laterally thereof and terminating in a loop portion clamped around a local point on a single turn of the filament coil so that said single turn extends through said loop portion of the support and is supported therefrom.

2. A lamp as set forth in claim 1 wherein the said intermediate part of the wire support member includes clamping legs extending from said loop to respective said straight wire sections.

3. A lamp as set forth in claim 2 wherein said clamping legs are curved in opposite directions and form, together with the said loop, a figure 8 providing a scissorlike effect and tightly enclosing the turn of said filament in said loop.

4. A lamp as set forth in claim 1 wherein the inner envelope wall has an indentation therein and the Wire support member has a portion thereof outwardly crimped forming a projection engaging in said indentation to prevent displacement of the support member longitudinally of the envelope.

5. A lamp as set forth in claim 1 wherein the inner envelope wall has an indentation therein and one of the circular turns of the wire support member has a portion thereof outwardly crimped forming a projection engaging in said indentation to prevent displacement of the support member longitudinally of the envelope.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN AN ELECTRIC INCANDESCENT LAMP COMPRISING A TUBULAR ENVELOPE HAVING THEREIN A HELICALLY COILED FILAMENT EXTENDING AXIALLY OF THE ENVELOPE AND SUPPORTED FROM THE INNER ENVELOPE WALL BY A WIRE SUPPORT MEMBER, SAID SUPPORT MEMBER COMPRISING A SINGLE LENGTH OF WIRE FORMED TO PROVIDE A PAIR OF CIRCULAR TURNS EXTENDING OVER AT LEAST HALF THE CIRCUMFERENCE OF THE INNER ENVELOPE WALL AND SPACED APART LONGITUDINALLY OF THE ENVELOPE, STRAIGHT WIRE SECTIONS EXTENDING TOWARD EACH OTHER FROM RESPECTIVE SAID TURNS LONGITUDINALLY OF THE ENVELOPE, AND AN INTERMEDIATE RETROVERTED LINK-LIKE PART BETWEEN SAID STRAIGHT SECTIONS EXTENDING LATERALY THEREOF AND TERMINATING IN A LOOP PORTION CLAMPED AROUND A LOCAL POINT ON A SINGLE TURN OF THE FILAMENT COIL SO THAT SAID SINGLE TURN EXTENDS THROUGH SAID LOOP PORTION OF THE SUPPORT AND IS SUPPORTED THEREFROM. 